Screen lining for a push-type centrifuge



Aug. 14, 1962 E. RUEGG SCREEN LINING FOR A PUSH-TYPE CENTRIFUGE 2 Sheets-Sheet 1 Filed Aug. 13, 1959 [V HM [L RLlfi 11g INVENTOR. Ern s: Ruegg BY ,J SW

Actornegs Aug. 14, 1962 E. RUEGG SCREEN LINING FOR A PUSH-TYPE CENTRIFUGE 2 Sheets-Sheet 2 Filed Aug. 13, 1959 S mm m mm .m R..... a n T E? United States Patent ()filice 3,049,241 Patented Aug. 14, 1962 SCREEN LINING FOR A PUSH-TYPE CENTRWUGE Ernst Ruegg, Kusnacht, Switzerland, assignor to Escher Wyss Aktiengesellschaft, Zurich, Switzerland, a corporation of fiwitzerland Filed Aug. 13, 1959, Ser. No. 833,534 Claims priority, application Switzerland Sept. 19, 1958 6 (Tlaims. (Cl. 210-376) This invention relates to a screen lining for the centrifugal drum of a push-type centrifuge, having barshaped members extending in the direction of the drum axis, which members have glide surfaces along which the material being centrifuged is pushed through the drum.

if the centrifuged material is delicate, the solid particles pushed over the glide surfaces may be damaged or made unattractive. When centrifuging sugar, for example, the edges and faces of the crystals may be worn ofi and the crystals lose their brilliance and become dull in appearance.

In addition, the glide surfaces on the members of the screen lining are subject to considerable wear.

Due to the glide stresses set up, therefore, the value of the discharged centrifuged material is reduced and at the same time the screen lining is damaged, this plating consisting of expensive materials, the chemical composition of which usually has to be adapted to the nature or intended use of the centrifuged material.

It is now the object of the invention to avoid the aforesaid disadvantages. In a screen lining of the kind hereinbefore described, trough-shaped depressions are provided for this purpose according to the invention in the glide surfaces of the screen lining members.

Constructional examples of the subject of the invention are illustrated in simplified representation in the drawing, wherein:

FIGURE 1 shows an axial section through a push-type centrifuge, and

FIGURES 2 to 4 are perspective views of series of different screen members.

The push-type centrifuge shown in FIGURE 1 has in a housing 1 a centrifugal drum 2 with a screen lining comprising screen members 3. An inlet hopper 4 supplies the material to be centrifuged, a pusher plate 5 pushes the material over the screen surface of the drum 2, when it is given an axial reciprocating movement.

As will be seen from FIGURE 2, the screen members 3 have trough-like depressions 7 in their glide surfaces 6. A portion of the liquid extracted from the centrifuged material will be retained in these depressions, while the greater portion of the liquid will pass over the trough edges into the gaps between the screen members or directly into said gaps and leave the centrifuge.

The liquid retained in the trough-like depressions now acts as a lubricant film between the material being centrifuged and the screen members. This lubrication considerably reduces the wear on the centrifuged material and on the screen lining. In this way, the solid substance of the centrifuged material can be obtained and discharged from the centrifuge in a high-grade condition, the life of the centrifugal screen can be increased and the work of discharge reduced.

In the members 3 shown in FIGURE 2, the glide surfaces in the region 3 covered by the pusher plate 5 is not interrupted. The trough-like depressions 7 commence in the throughput direction of the centrifuged material only after the region over which the reciprocating pusher member passes.

To prevent the liquid retained in the depressions 7 from being discharged along with the solid substances at the discharge end of the drum, perforations 8 are preferably provided there in the members 3 for the discharge of the said liquid.

The troughs could extend, however, over the entire length of the members and could be open in the axial direction at the inlet and/ or outlet end of the members.

The screen members shown in FIGURE 3 consist of plate strips 9. In the region of the reciprocating pusher member 5, said plates have a flat part 9 This part, however, could also be curved in accordance with the radius of the centrifugal drum. Along the adjoining portion 9 the plate strips are curved trough-like and at the discharge end, there follows a part 9 which is curved in roof fashion, i.e., provided with an'inward transverse how.

The bar-like screen members may be connected together. The screen members shown in FIGURE 4 consists of a single plate 16, divided by slits into individual members 11. These members 11 are here provided with pressed-in corrugations 12 forming the troughs.

The said slits may be produced for example in a simple manner by means of plate shears. Instead of pressing in the corrugations, the strips 11 could also be curved for example by bending.

Vvhat is claimed is:

1. In a push-type centrifuge having a rotary foraminous drum, a screen lining comprising bar-shaped members extending in the direction of the drum axis and spaced circumferentially over at least a portion of their lengths to define radial openings through which separated liquid may pass, the members having glide surfaces along which the material being centrifuged is pushed through the drum; and means for retaining a pool of liquid on each of said bar-shaped members comprising a longitudinal groove in the inner surface thereof extending over a substantial portion of said glide surface, whereby wear of the barshaped members and dam-age to the material being proc essed are reduced.

2. The combination defined in claim 1 in which a portion of the axial length of each glide surface is provided viti an inward transverse bow.

3. The combination defined in claim 1 in which the bar-shaped members are provided with perforations for the discharge of liquid retained in the grooves.

4. The combination defined in claim 1 in which the bar-shaped members consist of plate strips curved at least in part of their axial lengths to define said grooves.

5. The combination defined in claim 4 in which a portion of the axial length of each plate strip is provided with an inward transverse bow.

6. In a centrifuge of the type including a rotary foraminous drum for separating the solid and liquid components of the material being centrifuged, a pusher member encircled by the drum and axially shi-ftable therein, means for feeding the material to be centrifuged into the drum; said drum having an inside screen lining comprising barshaped members extending in the direction of the drum axis and spaced circumferentially over at least a portion of their lengths to define radial openings through which separated liquid may pass, the members having glide sur- 3 4 faces on which the material being centrifuged is pushed References Cited in the file of this patent through the drum when the pusher member is given an UNITED STATES PATENTS axial reciprocating movement; and means for retaining a pool of liquid on each of said bar-shaped members 1,246,035 1917 comprising a longitudinal groove in the inner surface 5 1,969,178 Klrby 1934 thereof extending over a substantial portion of said glide 2,720,982 Stuart 1955 surface axially outside the region over which the recipro FOREIGN PATENTS eating pusher member passes, whereby Wear of the bar- 578 202 Great Britain June 19 1946 shaped members and damage to the material being proc- 774,137 France a No 30 1934 essed are reduced. 10

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